Described herein is a photoconductive member, and more specifically a layered member that comprises an overcoat layer that includes a cured or substantially crosslinked product of at least a melamine-formaldehyde resin, optionally a phenol compound, and a charge transport compound.
The photoconductive members described herein may be used in, for example, electrophotographic imaging devices and xerographic imaging devices, printing processes, color imaging processes, copying/printing/scanning/fax combination systems and the like. The photoconductive member may be, for example, a photoreceptor, and may have any suitable form, for example plate or drum form.
Photosensitive members such as electrophotographic or photoconductive members, including photoreceptors or photoconductors, typically include a photoconductive layer formed on, for example, an electrically conductive substrate or formed on layers between the substrate and photoconductive layer. The photoconductive layer is an insulator in the dark, so that electric charges are retained on its surface. Upon exposure to light, the charge is dissipated, and an image can be formed thereon, developed using a developer material, transferred to a copy substrate, and fused thereto to form a copy or print.
Advanced imaging systems are based on the use of small diameter photoreceptor drums. The use of small diameter drums places a premium on photoreceptor life. A factor that can limit photoreceptor life is wear. Small diameter drum photoreceptors are particularly susceptible to wear because about 3 to 10 revolutions of the drum may be required to image a single letter size page. Multiple revolutions of a small diameter drum photoreceptor to reproduce a single letter size page can thus require about 1 million cycles or more from the photoreceptor drum to obtain 100,000 prints, one desirable print job goal for commercial systems.
For low volume copiers and printers, bias charging rolls (BCR) are desirable because little or no ozone is produced during image cycling. However, the microcorona generated by the BCR during charging damages the photoreceptor, resulting in rapid wear of the imaging surface, for example, the exposed surface of the charge transport layer. More specifically, wear rates can be as high as about 10 microns per 100,000 imaging cycles.